Daily rhythm studies
I teach middle school band/orchestra/guitar classes. One of the most important things I teach besides note reading is rhythms. My students will practice and study rhythms everyday in different formats.
On one note, chord, bowing
Call out rests
Just as reading notation being important, if you can't play rhythms correctly, you have nothing. One of the most difficult practices is using a metronome in your learning. Playing slow is difficult. We make sure we spend time practicing rhythms at quarter = 60bpm.
We will even incorporate rhythms examples with scales to reinforce a concept. This is something I got from my bass teacher, Max Janowsky. Putting one measure rhythms into context with scales makes playing less boring and more effective. Make sure you incorporate a metronome in your daily rehearsals. I feel that young orchestras need to do this more often. (I will write more about this in an upcoming blog about rhythmizing the bow)